Wireless-telegraph receiving system.



No. 852,381 PATENTED APR, 30, 1907. L. DE FOREST.

WIRELESS TELEGRAPH RECEIVING SYSTEM.

APPLICATION FILED DEO.4,1905.

2 SHEETS-SHEET 1.

' L. DE FOREST. WIRELESS TELEGRAPH RECEIVING SYSTEM APPLICATION FILED DEO.4, 1905.

PATENTED APR. 80, 1907.

UNiTED LEE DE- FOBEST, OF NEW YORK, N. Y;, ASSIGNOR TO GEORGE K. WOOD- WORTH, OF BOSTON, MASSACHUSE FS.

Specification of Letters Patent.

Patented April 30, 1907.

Application filed December 4, 1905. Serial No. 290,064i.

To all wit/mi it may cmwm'n:

Be it known that 1, LEE DE Fonns'r, a citizen of the Unitcd States, and a resident of how York. in the county of Now York and State of i York, have invented a new and useful ii OT/81710113 in Nircless-i fclcgraph Ii i" a Systems, of which the following is a specincuiion.

My invcntion rola ,s to Wireless telegraph receiving systems and has for its ohjccts certain new and improvcd apparatus and circuit arrangements whereby the receiving circuit containing a receiver or rcspondcr and the receiving antenna may each be udjustcd to the frequency or rate of vibration of tho cloctromugnctic waves intended to affect said rcs ceiver; and whereby thc cil'cct oi cxtrancous electrical forces, such as atmosphcric cloctricity or static charges, which are not intended to ail'cct said rcccivcr, may lac halanccd and thereby ncutralizcd, and hcncc prevented from ail'ccting said rccci vcr.

For tho purposc ol more full disclosing my invention 1 havc illustrated in thc drawings accompanying and forming a part oi this specification scvcral forms of apparatus and circuit arrangcmcnls which in practicc l have found vcll adaptcd for tho purposc ol carrying the hcrcinlwi'orc siatcd olijccis inlo cll'cct; but it will hc undcrslood that l do not linlii inyscli' to said forms of apparatus and circuit arrangements inasmuch as many 1nodiiicaiions may lnmadc liu-l'ci11\\'ill1oui dc )arting from tho spirii ol" my invcniion:

n the drawings, l igurc l rcprcscnls in diagroin a wirclcss tclcgraph rccciving syslcm icinhodying my invcntion; Fig. 2 rcprcscnts a modification of tho sysicm shown in Fig. l und Figs. 3, 4 and 5 rcprcscnt dclails oi construction;

iicicrring morn particularly to Fig. 1,.\ represents a. loop nutcnna oi ihc gcncrol typo descrihcd in my prior palcnts and l, l arc two coils serially conncctcd in said antcnna, and constituting the primary windings of a transformer, the sccondarv winding oi which consists of the coil S which-forms part of the tuned receiving circuit containing tho condenser C and receiver B. As has long been known in the practice of wireless tclegra-phy, it is desirable to adjust the antenna and the circuit containing the receiver to the fr0- quency of the electromagnetic Waves which are intended to afict the receiver, ahd this,

in thc present case, I accomplish hv variable 5 5 inductances constructcd in the following manner: Upon a plstcii or ii of glass or other insulating material is formed a Hat spins (shownat I", in Fig. i, and at S, infFiQ'. 5) consisting of insulated Wire so tightli; 6o Wound that the adjacent convohitions are contiguous throughout their extent and the spiral 'forms'zi practically piano surface; and at a convenient point, such as i i or 12, it contactarm 1 or 2 is pivoted to the plate, or, if dcsircd, at two points, such as 13 and 14., two contact arms 4 and 5 arc pivoted to said plate. Each contact arm is made of conducting lililllfiiztl llllfll carries at a point near its outcr cnd a contact incmhcr p, g, r, or s of an suiiahlc construction which malics contact with tho convolutions of its spiral nlong tho arc shnywdfparh or paths 111 who]! the contact arm is rolatcd on'ils pivot, rho insulation hnving hccn lillllfi/Ml vl'rom the upper portion of thc couduciors forming tho spii'nls along said paths u (1. Th0 inncrmostjfconvolulion of cach spiral is brought out, io a hinding post. on tho platc, as shonn in Figs. 3, l and :3 ui .1 and lo l'orm onc tcrminal of So tho spiral and the pivot ol' cach contact arm l'orms tho othcr lcrminal. lIac-liplatojllfili is mountcd upon a hcavy hasc 15, Hi, 17 of slatc o;- othcr suitalllc nmicrial so that tho spirals i, i may ho movcd toward and away from cach othcr and tho spiral S, which prolcrahly is placcd hctivccn lhc spirals P, P, may ho movcd with rcspcct ihcrcto and so that whcn 011cc adjustcd in position, each spiral will rcmain in such position. It will 0 lic obvious that thc contact arms ol" tho oufcr spirals may l c graspi-d by tho operator and roiaicd upon ihcir pivots but that in order l0 rolalc tho contact arm of the inner spiral S, thc contact arm 2 must ho prolongcd to lorm a handle 3.

it will now hc apparent that .vhcn lhc spirals l. l and S arc placcd as shown in Fig. 3 and arc connnctcd as shown in diagram in Fig. 1, said spirals constitutc a translormcr, 10o tlic primaries P P of which arc serially conncctcd with the loop antenna A, and Lll0 sec ondary S of which is inductively related to said primaries and forms a part of tho rccciving circuit. When the apparatus has 10 hccn arranged and connected in this manner, the antenna and the receiving circuit may both readily be adjusted to any desired frccecdingly simple and effective wireless telequency by varying the positions of the contact arms 1, 2 and 5, thereby varying the in ductance of the spirals as Well as the number of effective convolutions thereof in a continuous, as distinguished from an intermittent, manner, and hence permitting an exceedingly fine adjustment, A

I prefer, as shown in Figs. 1 and l, to employ two contact arms with one of the primaries, herein shown as the spiral P, so as to be able'at will to cause the oscillations developed in the antenna to have either a differential or a conjunctional effect upon the secondary S and the receiving circuit of which said secondary forms a part. For example shown in Fig. 1, the magnetic fields devcloped in the spirals P and i will have a conjunctional effect upon the spiral S if the tcurrent flows through P and P in the same direction, and hence if it be desired that the magnetic fields developed in said spiralsl and'l have a differential effect upon the spiral S under said conditions of current flow, the antenna is disconnected from the pivot '14 of the contactarm 5 and is connected to the spiral at the point :0 while the point it is connected to the pivot 13 of the contact arm 4 as shown in 24 In the absence of interference by extraneous electrical forces it is desirable to have the oscillations passing through the coils i P exert a conjunctional effect on the coil S and in the presence of such interference it is desirable that such effect he a differential one as hereinafter explained. in any event, the connection of the antenna to the arm 5 or the arm 4 must be determined experimentally,

' for, as will be obvious, the direction of current flow through P and P at any given instantof time depends altogether upon the relation of the length of the electrical waves impinging upon the antenna to the length of the antenna itself.

In view of the foregoing, it will be seen that the spirals P, P and S each constitute an exgraph tuning device whereby the first object of my invention may he realized.

The second object of my invention may be effected by means of the above (.les .:ribcd transformers in the following manner: Vihen the receiving; operator perceives by the signal indications in the head telephone T, included in circuit with the receiver it and potentiometcr Q which regulates the current from the battery ll, that the reception of a message is being interfered with by outside electrir-al forces, natural or artificial, he first connects the primaries l P so that they will act differentially with respect to the secondary S. lie then adjusts the effective number of convolutions in (al h primary until the condition known as silence in the telephone is'atlained. To arrive at such condition, it is sometimes necessary to move theprimarics toward or away from each. other and, pa ssibly, as final adjustment, to move the sec ondary with il-{espeet to the primaries in order to balarigce the effect of any inequality of the two sides of the loop antenna. When such an adjustment has been obtained that the effects of the two primaries on the secondary are equal and. opposite, no electrical impulse whatever, -whether it be the impulse desied a to received, or a disturbing impulse,

static charge induced by natural causes in toe antenna, will have the sliqhtest effect on the receiver because the effects of such inipulses on the receiving circuit are new balanced and thereby neutralized. In order, therefore, to receive the signals intended for the receiving system, all that is necessary is to slightly disturb the aforesaid balance by slightly moving the arms of the primaries l impulses or other frequencies or for static charges and hence prevent such impulses and charges from influencing the receiver; but so far as the static charges are concerned, the explanation probably is found in the fact that the effects of such charges are unidirectional and that therefore the balance of such effects on the secondary is not disturbed by the slight change produced in the inductance by the aforesaid movement of one of the primaries, or of the arms thereof. lvhat ever the explanation may be, if have succeeded with the system herein described in receiving signals in the presence of this unusually large static influences which exist in tropical and seini-t ropical climates. A

The elimination of static effects may be accornplished also by the system shown in Fig. 2, in which one sideof the loop antenna A is connected to a circuit consisting of two branches m 11 n and m n which, by a conductor iontaining the condenser C, connected to earth at E. The two primaries l and P are serially connected in said branches, and

hence are seriallyconnectedwith the antenna, ,but otherwise the arrangement 'of spirals is the same as in Fig. l. The antenna is shown as a multiple loop antenna in Fig. 2 but it is to be understood that a single loop antenna may be substituted therefor. The wires of the multiple loop antenna are secured to the mast (not shown) by the spar K and are separated by the sprcaders F F which are held in the positions indicated by the guys (1 G provided with the strain insulators I I. The side of the antenna which is not connected to ermer is connected to earth at E who the adjustable inductance L, which var in by the sliding contact i. As indicated on dottc lines, this contact may take the position 15, thereby entirely cutting. outthe inductance L, and affording a nth ot'low impedance toearth for the outsi e electrical forces or static influences.

From the description above forth oi' the operation of the system shown in Fig. 1, the operation of the system shown in Fig. 2 willbe apparent, and it will also be apparent that in the system oiFig. 2, the inequality lN.GBElS&Ylly existing between the two sides of any loop antenna does not enter as a disturb- @gfior into the operation of balancing the streets developed in the primaries upon the secondary. In view "of the fact, as above stated, that the spirals P, Pfiand 5 consist of insulated Wire so tightly wound thaf; the adjacent convoluticns are contiguous throughout their extent, it will be apparent that the variation oi the inductance and the number of the effective convolutions of said spirals, which is effected by-flue rotation of the arms '1, 2, i and about their respective pivots, will be continuous as distinguished from iutei'rnittent for the reason that the contacts, with which said arms are rovided, do not completely leave one convo ution before ar riving on the adjacent convolution.

I am aware that flat spirals have heretofore been proposed for use as transformer windings in wireless telegraphy but I know of no case in which the inductance and the number of effective turns of such spirals can be varied in a continuous manner, thereby permitting the exceedingly line adjustments required for effective tuning and for the elimination of foreign impulses.

Having fully described my invention, 1 claim: i

.1. In a wireless telegraph receiving systom, the combination with a loop antenna and a tuned receiving circuit, of a transformer having two primary windings serially connected. in said loop. antenna and a secondary winding inductively related to said primary windings and forming part of said tuned receiving circuit.

2. In a wireless telegraph receiving system, the combination with a loop antenna and a tuned receiving circuit, of a transformer having as its primary windings two llat spirals serially connected in said loop antenna, and a secondary winding, also consisting of a flat spiral, inductively related to said primary windings and forming part of said tuned receiving circuit.

3. In a wireless telegraph receiving systern, the combination with a loop antenna and a tuned receiving circuit, of a transformer bovin two adjustable primary windings serially connected in said loop antenna,

tively related to said primary windings and forming part oi said tuned receiving circu t.

4. In a wireless telegraph receiving system, the combination with a iorip antenna and a tuned receiving circuit, of a transformer having two primary windings serially connected in said loop antenna, means whereby said transformer windings may be moved toward and away from each other, and a secondary winding inductively related to said primary windings and forming part of said tuned receiving circuit,

5. lna wireless telegraph receiving system, the combination with a loop antenna and n, tuned receiving circuit, of a transl'ormer having two primary windings serially connected in said loop antenna, a secondary wimling' inductively related to said primary windings and forming part of said tuned receiving circuit, and means whereby said sceondary winding may be moved with respect to said primary windings.

6. In a wireless telegraph receiving system, the combination with a loop antenna and a tuned receiving circuit, of a trans former having two primary windings serially connected in said loop antenna, a secondary winding placed between said primary windings and forming part of said tuned receiving, circuit and means whereby said secondary winding may be moved with respect to said primary wind i ngs.

'7. In a wireless telegraph receiving system, an antenna, a circuit consisting of two branches connecting said antenna to earth, a mo iransl'ornuu' having two primary windings each serially connected in a different one of said branches, and a secondary windin inductively related to said rimary wim ings and forming part of a tuner receiving circuit.

Shin a wireless telegraph receiving sys tem, an antenna, a circuit consisting of two branches connecting said antenna to earth, a transformer having two primary windings each serially connected in a different one of said branches, a secondary winding inductively related to said primary windings and formin part of a tuned receiving circuit, and a circuit connecting the upper end of said antenna to earth.

9. In a wireless telegraph receiving system, an antenna, a transformer having two primary windings associated therewith, a secondary winding inductively related to said rimarv windin s and means for causing the electrical oscillations developed in said antenna to have either a (inferential or 'a conjunctional effect on said secondary windmg.

, 10. The combination with a wireless tole- "[2 5 graph receiving antenna of an oscillation transformer consisting of three flat spirals, two of which are )IllllilllCS and one of which is a secondary am. hoavybascs each having a and an adjustable secondary winding inducdifferent one of said spirals mounted thereon 13 number of eil'eciire (ZODYOlH ions of said primaries and said S'.' 'f )d(l:1l v" may be "varied in a continuous manni r.

Tllc combination wirb a .'-.'ireless icle graph receiving unienna of an osciila: ion

transformer consisting of mm liar spirals. I

two of which are primaries and one ol' w dice is a secondary, said primari i strucied and arrau in art, dill'ci nliully upon said secondar means \rlicrcb said rimaries may be moved toward and away being run from each other and means wiiercby said sew ondary may be moved wi'rh respcri to said i may be moved wnli respectv to sand prn'nary primaries.

13. In a wireless telegraph receiving system, the combination with a loop antenna and a receiving circuit, oi s trai'isl'orlncr baring as iis primary windings two llat spirals seriallynconneeted in said loop antenna, a secondary winding, also consisting of a ilai spiral, inductively relmed to said primary windings and' forming part of said receiving circuit, iind means for varying the number of eli'eetive convoluiions of said list spirals.

14. The combinsrion with a wireless relegrapli receiving amenna of an oscil-lmion Lransibrmer consisling of three flatv spirals, two of which are primaries and one of which is a secondary. said primaries bcinp constructed and arranged to act dill'ercm'ially upon said'secondm'y and means w ereby said secondary may be moved wit h respect. lo said primaries.

15, in a wireless telegraph receiving system, an amcnna, a circuit consisting of iwo branches connwrin; said amenne lo earl b, a transformer having as its primary windings two flat spirals ear-b serially connected in adifl'ersnt one of ssidbrancbcs, and a secondary winding, consisting of a lat sp ral, inductively relaiacd to raid primary windings and forming pari oi a tuned receiving circuit.

16. In a wireless telegraph receiving system, an antenna, a circuitronsisting of two branches connecting said antenna to earth, a transformer having; two mljustable primary Xiil'!(illi;;:-' cscb serisily connected in a dill'ercnt; one, 7f said brsizcnes, end an z-uliustable secondary winding inductively rclarcd to said prii'nary nindingg-s and forming pzrrt of a tuned recciviircircun...

17. in a wireless telegraph receiving system, an amenna, a circuii consirfding of two branches connecting said antenna 1o earth, a transformer baring Lire primary windin ear-l1 serially connected in a diii'crem one of said branches. means whereby said transformer windings may be moved each with rosperr io lire oilicr, and a secondsrv windingizulnciivei related to said primary windings and forming part of a runed receiving circuir.

In, in a wireless iclcgrrepli receiring sys rem, an antenna, ac'

n uit consisting of two branc es runner-ring said antenna to earth, a nslornzer caring two prnnery windings said brew-m s, a secondary Winding induelively relaicd to said priumry windings and l'lnuiing park of a tuned receiving circuit, and means wbcreby said secondary winding findings ii ir- :1 wireless telegraph receiving tern, an auienns. e circ lit consisting of two branches cenncciing said antenna to earth, a transformer having two primary windings each serially connected in s difi'erent one of said brzmclics, a secondary winding placed.-

between said prim ary windings and forming part of a tuned receiving circuit, and means whereby said secoudin'jwinding may be moved wil'i respect: to said primary Wind- 2U. rem, an antenna, a. circuit consisting of two branches connecting said anfennzi to earth, a transformer liar ing as its primary windings two liar spirals, each serially connected in a diilercurone of said branches, means whereby the number of eii'eritire eonvolut-ions of said primary windings may be varied, a secondary winding, consisting of a flat spiral, induciively related to said primary windings and iorming part ol" :1. receiving circuit, and means whereby (be number of effective convolutions of said sei ondary winding may be Yaried.

in lest in]onywbcreof, l have hereunto subscribed my name this 29th day of Nov. 1905.

LEE DE FOREST.

Vii tnesses:

i Pnnyir Fannswon'rn,

C. 13. GALBnAI'rn.

in a wireless telegraph receiving sys 2m seriallv conncci-cd in a dil'l'erent one of ICI 

